Here's why:

* Bloodstone is a variety of chalcedony, which is a microcrystalline form of quartz.

* Chalcedony itself forms when silica-rich solutions deposit in the spaces within other rocks. This process often occurs in volcanic environments.

* Metamorphism happens when existing rocks are transformed by heat, pressure, and chemical reactions. In the case of bloodstone, the original rock (often a basalt) is altered by these processes, resulting in the characteristic red inclusions (hematite) within the green chalcedony.

Let me know if you'd like more details on the formation of bloodstone or any other rock type!